To date, these kind of weapon drive systems normally have hydraulic motors operating at constant displacement for the mass (turret) to be directed in transverse direction and hydraulic actuators with big volumes for the mass (weapon) to be elevated, while the turret adjustment is controlled by servo valves which obtain their hydraulic power from hydraulic pumps and accumulators. They are kept pressurized by an intermittent working pump.
Under certain circumstances these weapon drive systems can be dangerous for the tank crew, especially when the pressure reservoir is being damaged under bombardment.
Most of all, these weapon drive systems have a very poor efficiency, because the volumetric flow is controlled by servo valves. The resulting differential pressure leads to a significant oil temperature increase. Due to this, an additional heat exchanger is necessary.
Since the sectional area of the cylinders has to be quite large due to mechanical stiffness of motion, the system pressure cannot be freely selected. The only result of increased system pressure would be increased pressure losses at the servovalves.
In order to eliminate at least part of these disadvantages, electrical drive systems have been developed. These electrical systems are not as efficient as hydraulic systems (less power density), are too big and too heavy, and are unable to fullfil the requirements of gun laying speed and acceleration needed for heavy weapons.